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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

28085 results found.

  1. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  2. GRB 260303A: SVOM detection of a burst
  3. GRB 260228A: EP-FXT follow-up observation
  4. EP260302a: Einstein Probe detection of an X-ray transient
  5. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  6. GRB 251130B: TERI Gamma-ray detection
  7. GRB 260208A: TERI Gamma-ray detection
  8. EP260227a: Mondy optical observations
  9. GRB 260228A: CAHA 2.2m telescope optical upper limit
  10. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. EP260227a: Mephisto optical detection
  12. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  13. EP260227a: SVOM/VT optical observation
  14. GRB 260228A: SVOM/VT optical upper limits
  15. GRB 260225D: SVOM/GRM observation
  16. EP260227A: 3.6m DOT optical afterglow detection
  17. GRB 260225B: SVOM/GRM observation
  18. EP260227a: Liverpool Telescope optical observations
  19. EP260227a: LCOGT Optical Observations
  20. GRB 260226A: Asiago r-band upper limit
  21. EP260227a: Liverpool Telescope observations
  22. EP260227a: COLIBRÍ optical observations
  23. EP260227a: NOT optical observations
  24. EP260227a: Global MASTER-Net observations report
  25. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  26. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  27. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  28. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  29. EP260214a: VLT/FORS2 optical observations
  30. GRB 260225A: WINTER J-band upper limit
  31. GRB 260226A: COLIBRÍ optical upper limits
  32. GRB 260226A: LCOGT Optical Upper Limit
  33. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  34. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  35. GRB 260226A: Glowbug gamma-ray detection
  36. GRB 260226A: NuSTAR detection of bright prompt emission
  37. GRB 260226A : GROWTH-India Telescope optical observations
  38. GRB 260226A: LAST optical upper limit
  39. GRB 260226A: Fermi GBM observation
  40. LAT GRB260226.44: Global MASTER-Net observations report
  41. Fermi GRB 260226A: Global MASTER-Net observations report
  42. GRB 260226A: AstroSat CZTI detection of bright long burst
  43. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  44. EP260224a: LCO optical upper limits
  45. GRB 260225A: EP-FXT follow-up observation
  46. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  47. GRB 260223A: Fermi GBM Observation
  48. GRB 260225A: SVOM/VT optical upper limits
  49. EP260223a: Liverpool Telescope upper limits
  50. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  51. EP260224a: Einstein Probe detection of an X-ray transient
  52. EP 260225.148: COLIBRÍ Confirmation of flaring star
  53. EP260223a: Xinglong optical upper limit
  54. GRB 260223A: Glowbug gamma-ray detection
  55. EP260213a: Mephisto optical upper limits
  56. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  57. sb26021801: SVOM/C-GFT upper limit
  58. EP260223a: COLIBRÍ optical upper limits
  59. EP260223a: Einstein Probe detection of an X-ray transient
  60. GRB 260223A: SVOM/GRM observation
  61. GRB 260223A: COLIBRÍ further optical observations and a brightening
  62. EP260221a: Optical upper limit with Kinder observations
  63. GRB 260223A: COLIBRÍ optical observations
  64. GRB 260223A: DDOTI Optical Candidate
  65. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  66. Fermi GRB 260223A: Global MASTER-Net observations report
  67. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  68. EP260221a: COLIBRÍ optical counterpart candidate
  69. EP260221a: Gemini South z-band upper limit
  70. EP260221a: Global MASTER-Net observations report
  71. EP260221a: EP-FXT follow-up observation
  72. Fermi GRB 260221B: Global MASTER-Net observations report
  73. EP-WXT01709258519: Xinglong optical upper limit
  74. EP260221a: Xinglong optical upper limit
  75. Fermi GRB 260221A: Global MASTER-Net observations report
  76. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  77. EP260221a: GOTO optical upper limit
  78. EP260221a: COLIBRÍ optical upper limit
  79. SVOM alert sb26021801: LCO optical upper limit
  80. EP260221a: Einstein Probe detection of an X-ray transient
  81. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  82. Fermi GRB 260219A: Global MASTER-Net observations report
  83. SVOM alert sb26021801: LAST optical upper limit
  84. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. IceCube Alert 260217A: Global MASTER-Net observations report
  86. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  87. sb26021801: SVOM detection of a long faint X-ray transient
  88. EP-WXT 01709258455: NOT optical upper limits
  89. EP260214b: Mondy optical observations
  90. EP260214b: 1.3m DFOT optical upper limit
  91. EP260210a: Mondy optical upper limits
  92. GRB 260208A: AbAO and Terskol optical upper limits
  93. GRB 260208A: continued Mondy optical observations
  94. IPN triangulation of GRB 260212A
  95. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  96. EP260214b: Liverpool Telescope optical observations
  97. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  98. EP260214b: Optical upper limit with Kinder observations
  99. EP260214a: Optical upper limits with Kinder observations
  100. EP260214b: EP-FXT follow-up observation

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